Breeding success with ‘fat-bottomed cows’

How to achieve "fat-bottomed cows" — or rather, managing cow Body Condition Score (BCS) for breeding success — is among the topics covered in an engaging new overview of findings from the Beef + Lamb New Zealand Genetics Beef Progeny Test.

The series of short articles by scientist and "data wrangler" Dr Nicola Dennis brings to life scientific findings from the original Beef Progeny Test.

Topics covered include mature liveweight and growth, the genetics of BCS, increasing beef marbling without overflowing into external fat, carcass rib fat depth, and how ultrasound scanning can predict marbling in beef.

Spanning from 2014 to 2023, the Progeny Test compared bulls under New Zealand farming conditions.

B+LNZ Genetics has been analysing the dataset collected from those farms to identify valuable insights for stud breeders and commercial farmers.

It has since evolved into an across-breed Beef Progeny Test as part of the Informing New Zealand Beef (INZB) programme supported by B+LNZ, the New Zealand Meat Board, and the Ministry for Primary Industries’ Sustainable Food & Fibre Futures fund.

The across-breed Progeny Test uses Angus, Hereford and Simmental genetics to identify the performance of agreed-on traits.

Dr Dennis looks at how recording more carcass data is proving important in helping to identify those animals that are heavy on the hook from more moderate-sized cows.

B+LNZ geneticists have also been looking closely at the relationship between rib fat depth and marbling — analysing data from more than 2100 Beef Progeny Test cattle. The findings suggest there is scope to identify bulls that have high marbling scores without excessive rib fat depth.

That links into some interesting outcomes from the scanning of 4500 cattle for carcass traits, with many also scored for marbling at processing.

As for those fat-bottomed cows, Dr Dennis says they make the rocking farm go round. She outlines how analysis of Beef Progeny Test findings has pinpointed a linear relationship between cow BCS and conception rate.

"So when it comes to divvying up the pasture pie, it makes sense to focus on fattening up the skinny minnies rather than trying to put extra love handles on already well-conditioned cows."

Of course, there’s rather more to it than that. To read the articles in full, see and click on "View Beef Progeny Test Outcomes". — Beef + Lamb New Zealand